Discharge printing



Patented Nov. 27, I934 1,981,907 DISCHARGE PRINTING Frederick Baxter Downing, Carneys Point, N. 1., and Richard Gesse Clarkson, Wilmington, Del., assignorsto E. I. du Pont de Nemours & Com-- pany, Wilmington, ware No Drawing.

Del., a corporation of Dela- Application May 15, 1931,

I Serial No. 537,748

11 Claims.

cyanate as a swelling agent for cellulose acetate textile material.

There is a type of textile printing known as the discharged dyed style. In general this process comprises dyeing'the fabric throughout and thereafter printing on certain portions or areas thereof what is known as a discharge paste. This paste is a composition comprising some substance or substances capable ofremoving, destroying or permanently decoloring the dye already afiixed to the fabric. Upon suitable after-treatment the color is removed at the places in contact with the discharge paste.

There is a modification of the above described process known as color discharge printing which is generally the same except that the discharge paste comprises another dye, so that upon discharge of the'original dye from the dyed fabric the second dye (that is, the dye inv the discharge paste) remains on the discharged portion. As will be obvious the second -dye is of a type which is not adversely affected .by the color discharging materials present in the paste.

So far as the art is at present advised it appears that the dyeing of cellulose acetate and the like is a different phenomena from the dyeing of other fibers. Cellulose acetate is dyed by reason of theformation of the solid solution of the dyestuff in the fiber. The dyeing of other fibers results from the adsorption of minute particles of the'dyestuff upon the surface of the fiber (Brandenberger Textiliber 10, 215, 461: 1929).

In the production of discharge effects the reduction discharge methods, previously in general use, were based upon the use of sodiumformaldehyde-sulfoxylate as a discharging agent. While satisfactory discharges may be produced upon silk, wool and cotton with this substance it is inefiective when applied to the cellulose acetate type of fiber. For this reason the art of producing .discharges upon cellulose acetate has advanced along two lines. The first of these lines of development is based upon the use of a discharging agent other than sodium-formaldehyde-sulfoxylate. As an example of this development mention may be made of the disclosure by Fischesser (US. Patent -tragacanth in 1000 parts of water.

1,747,540 of Feb. 18, 1930) relating to neutral zinc sulfoxylate as a discharging agent. The other line of development continues the use of the sodium-formaldehyde-sulfoxylate previously known but utilizes in conjunction therewith a swelling agent. A swelling agent may be defined as a substance which will swell the fiber and. permit its penetration by a reducing or decoloring agent. The term swelling agent is well known in the art. The use of a swelling agent in addition to the sodium-formaldehydesulfoxylate is disclosed broadly by Ellis and Greenhalgh (U. S. Patent 1,792,152 of Feb. 10, 1931). A later development along this line is that of Smith (U. S. Patent 1,651,639 of Dec. 6, 1929) which shows the suitability of the specific swelling agents, ammonium sulfocyanide, calcium sulfocyanide and barium sulfocyanide. With many dyes, however, eventhe useof these last named substances has not given a reduction sufficiently complete to be commercially practical.

This invention has as an object the provision of a method for producing clear and white discharges upon fabrics composed Wholly or in part of cellulose esters or ethers. Further objects are the discharging of dyes which have not heretofore been dischargeable upon fabrics containing such cellulose derivatives, the provision of new color discharge printing processes and effects on cellulose esters or ethers, the provision of new relustering processes for cellulose esters or ethers, and in general an advancement of the art. Other objects will appear hereinafter.

These objects are accomplished by the present invention according to which zinc thiocyanate is incorporated in discharge printing pastes. The invention will be readily understood from a consideration of the following examples and description in which the parts are given by weight.

Discharge printing paste Twenty (20) parts of sodium-formaldehydesulfoxylate were dissolved -in 55 parts of gum tragacanth solution containing 60 parts of gum This solution was accomplished at about 60 C. When the sulfoxylate was in complete solution 10 parts of solid zinc thiocyanate and 15 parts of diethylene glycol were added.

Example I A fabric composed of cellulose acetate was dyed in the customary manner with Ionamine A powder (para amino para dimethyl amino customary manner. 30.

azobenzeneomegamethylsodium sulfonate) and was afterwards diazotized and coupled with B-hydroxy-naphthoic acid. The material was then printed with the discharge printing paste described above. After the fabric had been printed it was dried and aged for 3-5 minutes in an ordinary type of rapid ager at 100 C. It was then washed in water at 60 C. for 3 minutes and dried. A pure white discharge was obtained.

For sake of comparison with the disclosure in the patents above cited the procedure of Example I was repeated with a similar discharge'paste containing 20 parts of zinc formaldehyde-sulfoxylate, no sodium-formaldehyde-sulfoxylate and no zinc thiocyanate. The resulting discharge had a strong yellow cast. The first procedure was markedly superior. The process of Example I was also carried'out with a similar discharge in which ammonium thiocyanate had been substituted for the zinc thiocyanate. The material was scarcely afiected by this discharge paste.

Example II A fabric composed of cellulose acetate was dyed with Cellitazol ST (General Dyestufis Corporation) and was afterwards diazotized and coupled with fl-hydroxy-naphthoic acid in the It was then printed and after-treated as described in Example I. The discharge areas obtained were clear and white.

Example III Material composed of cellulose acetate was dyed in the customary manner with Cibacete Diazo Black B (Ciba Company, Inc.) and was afterwards diazotized and coupled with hydroxy-naphthoic acid. The material was then printed and after-treated as described in.

Example I. The resultant discharge had a slightly yellowish tone. -As in Example I a comparison was made using ammonium thiocyanate in the discharge paste but no appreciable discharge was produced.

Example IV Material composed of cellulose acetate was dyed in the customary manner with Cellitazol AZ (General Dyestuffs Corporation) and afterwards diazotized and coupled with p-oxy-naphthoic acid in the usual way. The material was r then printed with the colored discharge printing paste made up as follows:

Fifteen (15) parts by weight of British gum were dissolved in 24 parts of gum tragacanth solution, containing 80 parts of gum tragacanth in .1000 parts of .water, by heating. This thickener was then divided into two portions (A) containing 30 parts and (B) containing 9 parts. Twenty (20) parts of sodium-formaldehyde-sulfoxylate were then dissolved in portion A and afterwards 15 parts of di-ethylene glycol and 10 parts of zinc thiocyanate were added. In portion B there was dissolved 6 parts of sodium hydroxide solution containing 300 parts of so- 'dium hydroxide in 700 parts of water. The two After the fabric had been printed it was aged 3-5 minutesin the ordinary type of rapid ager at 100 C. It was then washed in water at 60 outlines on a black ground was obtained.

When the above procedure was repeated with t the substitution of 10 parts of sodium-sulfocyanide for 10 parts of zinc thiocyanate the-shade of the printed design was dulland weak.- The outlines of the design were halo-ed, poorly defined and indistinct.

In the discharge pastes above described alkali metal formaldehyde-sulfoxylates other than sodium, for example, potassium, may be used satisfactorily.

While in the above examples di-ethylene glycol has beenutilized it is to be understood that other high boiling water soluble organic swelling agents for cellulose esters and ethers may be utilized satisfactorily. Because of its price and the results producible when it is used, di-ethylene glycol is preferred. Other compounds, such as glycerol, di-acetone alcohol, glycerol monoacetate, ethylene glycol, ethyl-lactate, glycerol .a-mono-chlorhydrin, di-ethylene glycol-monoacetate, glycerol di-acetate, and ethylene glycolmono-acetate, are so satisfactory as to merit special mention.

The amounts of zinc thiocyanate and of high boiling water soluble organic swelling agent which should be added to the discharge paste to produce a satisfactory discharge, vary so widely that definite limits cannot be given. The

amount to be used depends upon the nature of the fabric, the weave of the cloth, the size of the filaments, the nature of the dyestuif employed, the strength of the dyeing and the like.

No general rule can, therefore, be laid down as L to the amount of the reagent to be employed. 1

For each specific case this may be readily determined by experiment by one skilled in the art.

Variations in the discharging conditions may be made if desired.

Zinc thiocyanate may also be used in color printing on acetyl cellulose and the like.

Among the numerous and outstanding advantages of this invention there may be mentioned the production of discharges of a character unobtainable by previously known methods. This is especially true of the more diflicultly dischargeable colors such as those of the examples.

The production of discharge efiects characterized by much less delustering than results from the use of the known thiocyanate discharge paste is also an important result.

As many apparently widely different embodi- 3. A cellulose-ester and ether dye dischargingpaste comprising an alkali-metal-formaldehydesulfoxylate, di-ethylene glycol. and zinc thiocyanate. 4. A cellulose-ester and ether dye discharging paste comprising an alkali-metal-formaldehyde-. sulfoxylate and zinc thiocyanate.

5. As a new composition of matter, a preparation for the production of discharge eflfects on materials containing cellulose esters or ethers, comprising an alkali-metal-formaldehyde-sulfoxylate discharge printing paste and also comprising a high boiling water soluble organic swelling agent and zinc thiocyanate.

- 6. As a new composition of matter, a preparation for the production of discharge efiects on materials containing cellulose esters or ethers, comprising a gum of the type generally employed in discharge pastes, a reducing" agent of the hydrosulfite class, and zinc thiocyanate.

'7. A" process for producing colored patterns on material comprising celluloseesters or ethers comprising dyeing said material with a dischargeable dyestufi, and then applying thereto locally aficomposition comprising zinc thiocyanate, and a sulfoxylate capable of efiecting a color change.

8. A process for producing colored patterns on material comprising colored cellulose esters or ethers comprising locally applying to said material a composition comprising zinc thiocyanate and a sulfoxylate capable of dischar in the color thereon.

9. A process for producing colored patterns on material comprising cellulose esters or ethers comprising dyeing said material with an azo dyestuff and then applying thereto locally a composition comprising zinc thiocyanate, a sulfoxylate capable of discharging the color thereon and material capable of effecting a color change.

10. The process which comprises printing a discharge composition containing zinc thiocyanate, a sulfoxylate and a member of the group consisting of (ii-ethylene glycol, glycerol, di- ,1

type generally usable on cellulose ester material,

and zinc thiocyanate. I

FREDERICK B. DOWNING. RICHARD G. CLARKSON. 

